Sam Childers was one bad dude. Fresh out of prison, he was up to no good—drinking, drugging, stealing, fighting, you name it. Then the Pittsburgh native found God, got his act together and ended up in Africa, where he built an orphanage for children left parentless by war. He fought for what’s right.

Childers’ story is the focus of Machine Gun Preacher, an inspired-by-truth film that, while uneven in some aspects, is well worth seeing as a rental. Gerard Butler (best known as the lead six-pack in 300) plays Childers with a tough-guy authenticity and vulnerability that elevates the film from just playing as an Americans-saves-Africans parable. This film isn’t afraid to get gritty and real in its early scenes depicting just how down and dirty Childers got.

While Machine Gun Preacher may be viewed by some as a Christian film—as it’s Childers’ religious conversion that fuels his charitable efforts—the movie doesn’t beat you over the head with its spirituality. It has grittiness in language, violence and sexuality—this is a film made for adults, not church groups.

Directed by Marc Forster (Monster’s Ball) from a screenplay by Jason Keller based on Childers’ book, Machine Gun Preacher is not without its flaws. Some story points are not well-explained. It can be hard to follow at times. It just sort of ends with no real conclusion—just a slice of life. And Forster and Keller are certainly not above manipulating the audience with the reformed Childers’ suddenly saintly behavior.

But the performances of Butler, Michelle Monaghan as his wife, and the creepy-eyed Michael Shannon as his good-times buddy—as well as the power of Childers’ story and accomplishments—make this a inspiring, moving, compelling film experience.

As well, the photography of the African locations is well represented on Blu-ray. I didn’t expect much from this film (the misleading title suggests an empty-headed action epic, and it’s far more substantive than that), but it’s surprisingly watchable and compelling in its way.